Laboratory visualization of damage asymmetry formation of rock fracture via acoustic emission and digital imaging correlation

Abstract

Rock fracture mechanics and accurate characterization of rock fracture are crucial for understanding a variety of phenomena interested in geological engineering and geoscience. These phenomena range from very large-scale asymmetrical fault structures to the scale of engineering projects and laboratory-scale rock fracture tests. Comprehensive study can involve mechanical modeling, site or post-mortem investigations, and inspection on the point cloud of the source locations in the form of earthquake, micro-seismicity, or acoustic emission. This study presents a comprehensive data analysis on characterizing the forming of the asymmetrical damage zone around a laboratory mixed-mode rock fracture. We substantiate the presence of asymmetrical damage through qualitative analysis and demonstrate that measurement uncertainties cannot solely explain the observed asymmetry. The implications of this demonstration can be manifold. On a larger scale, it solidifies a mechanical model used for explaining the contribution of aseismic mechanisms to asymmetrical fault structures. On a laboratory scale, it exemplifies an alternative approach to understanding the observational difference between the source location and the in situ or post-mortem inspection on the rock fracture path. The mechanical model and the data analysis can be informative to the interpretations of other engineering practices as well, but may face different types of challenges.